It seems just about all the garages have switched from 10w30 to 5w30. This isn't really optimal for those of us with older cars (>10yrs), and my manual specifically states 5w30, though okay for the winter temps, is not recommended for higher temperatures. Has the quality of oils improved since then, that is now okay to use this oil?

 

I know it isn't optimal for my 95 ej18 engine. Would adding half a qt of 20w50 or straight 40 help much?

I would run 10w30. The tolerances of the newer engines are tighter, so they need to run thinner oil. Plus it's more fuel efficient.

It seems just about all the garages have switched from 10w30 to 5w30. This isn't really optimal for those of us with older cars (>10yrs), and my manual specifically states 5w30, though okay for the winter temps, is not recommended for higher temperatures. Has the quality of oils improved since then, that is now okay to use this oil?

 

I know it isn't optimal for my 95 ej18 engine. Would adding half a qt of 20w50 or straight 40 help much?

 

Yes, the quality improved. It doesn't shear down as much like it used to.

But if I were you I would use 10W30 summer, 5W30 winter, OR high milage 5W30 (they start with higher viscosity than regular) all the time.

 

Now, if you use all the ponies you have (racing, towing), use XW40 oils in summer.